Difference between revisions of "PERL/C2/Functions-in-Perl/English-timed"
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PoojaMoolya (Talk | contribs) (Created page with '{| border=1 ! <center>'''Visual Cue'''</center> ! <center>'''Narration'''</center> |- | 00.01 |Welcome to the spoken tutorial on ''' Functions in Perl'''. |- | 00.06 | In th…') |
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Revision as of 15:26, 28 May 2014
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| 00.01 | Welcome to the spoken tutorial on Functions in Perl. |
| 00.06 | In this tutorial, we will learn about - |
| 00.10 | Perl functions |
| 00.11 | functions with arguments |
| 00.13 | function with return values |
| 00.16 | For this tutorial, I am using |
| 00.18 | Ubuntu Linux12.04 operating system |
| 00.22 | Perl 5.14.2 and |
| 00.24 | gedit Text Editor |
| 00.27 | You can use any text editor of your choice. |
| 00.31 | You should have basic knowledge of variables, comments, loops, conditional statements and Data Structures in Perl. |
| 00.41 | Please go through the relevant spoken tutorials on the spoken tutorial website. |
| 00.47 | We will first see some simple Perl functions.
|
| 00.51 | In Perl, functions, also called as subroutines, are declared with sub keyword.
|
| 00.57 | The definition of a declared function is written between curly braces. |
| 01.03 | This function does not take any arguments. |
| 01.07 | And, it does not return anything. |
| 01.10 | Note: function definition can be written anywhere in the script or in another module. |
| 01.17 | This module, must then be included in the script, to use this function. |
| 01.24 | To include the module file in the script, one has to use the following syntax-
|
| 01.31 | use ModuleFileName semicolon
|
| 01.35 | Let us understand this using a sample program. |
| 01.39 | Open a file in your text editor and name it as simpleFunction dot pl |
| 01.46 | Here is my simpleFunction dot pl file in gedit.
|
| 01.51 | Type the code as displayed on the screen. |
| 01.55 | Here, we are just calling a function, which we have defined.
|
| 02.00 | Then, the execution control is passed to that function.
|
| 02.06 | This is the declaration & definition of the function. |
| 02.10 | This function will print out the given text.
|
| 02.14 | Save your file. |
| 02.17 | Then switch to the terminal and execute the Perl script by typing |
| 02.24 | perl simpleFunction dot pl |
| 02.28 | and press Enter. |
| 02.30 | The output will be as shown on the terminal |
| 02.38 | Now, let us see a function with arguments.
|
| 02.44 | Let us understand this function using a sample program.
|
| 02.48 | Open a file in your text editor and name it as functionWithArgs dot pl |
| 02.57 | Here is my functionWithArgs script in gedit.
|
| 03.02 | Type the following piece of code as shown on the screen. |
| 03.07 | Here, we are calling a function with arguments, 10 and 20. |
| 03.13 | The passed arguments are caught in $var1 & $var2. |
| 03.20 | @_ is a special Perl variable. We will cover its details in future tutorials.
|
| 03.29 | This function performs the addition of 2 variables and prints the answer. |
| 03.37 | Save your file.
|
| 03.42 | @_ is a special Perl array.
|
| 03.46 | This array is used to store the passed arguments.
|
| 03.51 | Similarly, we can catch the passed arguments in variables as |
| 03.56 | $var1 space = space shift @_ semicolon
|
| 04.04 | $var2 space = space shift @_ semicolon
|
| 04.12 | shift @_ removes the element at first position from @_ array |
| 04.21 | and assigns it to a variable
|
| 04.24 | Another way is; $var1 space = space dollar underscrore open square bracket zero close square bracket semicolon |
| 04.38 | $var2 space = space dollar underscrore open square bracket 1 close square bracket semicolon |
| 04.49 | The above mentioned way is similar to fetching elements of @_ array using index.
|
| 04.59 | Now, switch to terminal and execute the script by typing - |
| 05.06 | perl functionWithArgs dot pl and press Enter
|
| 05.14 | The output is as displayed on the screen |
| 05.23 | Now, let us look at a functions which returns a single value.
|
| 05.32 | Let us understand the same using a sample program. |
| 05.35 | Let me switch to funcWithSingleRtrnVal dot pl script in gedit. |
| 05.46 | Open a file in your text editor and type the following piece of code as shown. |
| 05.52 | Here, we are calling addVariables function with parameters 10 and 20. |
| 06.01 | The return value of the function is caught in $addition variable. |
| 06.09 | This function does the addition of the passed parameters and returns the answer.
|
| 06.15 | Save the file.
|
| 06.17 | Now let us execute the script. |
| 06.20 | So, switch to terminal and type- |
| 06.24 | perl funcWithSingleRtrnVal dot pl and press Enter.
|
| 06.35 | The output is as displayed on the terminal.
|
| 06.43 | Now, let us see a function which returns multiple values.
|
| 06.48 | Let us understand the same, using a sample program. |
| 06.53 | In gedit, I have opened a file and named it as funcWithMultipleRtrnVals dot pl |
| 07.04 | Please do like wise in your text editor |
| 07.08 | Now, type the following piece of code as shown. |
| 07.13 | Here, we are calling addVariables function with parameters 10 and 20. |
| 07.21 | The return values of the function are caught in variables $var1, $var2 and $addition |
| 07.31 | This function does the addition and returns the passed parameters and the resultant answer. |
| 07.42 | This illustration demonstrates how we can return an array from a function. |
| 07.53 | Similarly, this demonstrates how hash can be returned from a function.
|
| 08.00 | Save your file.
|
| 08.03 | Now let us execute the Perl script on the terminal by typing - |
| 08.10 | perl funcWithMultipleRtrnVals dot pl |
| 08.18 | and press Enter. |
| 08.20 | The output is as displayed on the terminal. |
| 08.32 | Perl provides several inbuilt functions.
|
| 08.36 | We learnt some of them in earlier tutorials. For eg- Arrays, Hash, sort, scalar, each, keys etc. |
| 08.49 | Calling inbuilt functions, similar to calling any other function, which we define. |
| 08.57 | E.g sort open bracket @arrayName close bracket semicolon |
| 09.04 | Try incorporating some inbuilt functions in the sample programs we used. |
| 09.10 | And observe their outputs. |
| 09.13 | Let us summarize. |
| 09.15 | In this tutorial, we have learnt - |
| 09.17 | Functions in Perl |
| 09.19 | functions with arguments and |
| 09.22 | functions which return values using sample programs. |
| 09.27 | Here is assignment for you - |
| 09.29 | Write a function which takes 3 arguments. |
| 09.33 | Perform some action on these arguments |
| 09.37 | Return the result of the action performed on the arguments and print the same.
|
| 09.43 | Watch the video available at the following link
|
| 09.47 | It summaries the Spoken Tutorial project
|
| 09.51 | If you do not have good bandwidth, you can download and watch it |
| 09.56 | The Spoken Tutorial Project Team Conducts workshops using spoken tutorials
|
| 10.02 | Gives certificates to those who pass an online test |
| 10.07 | For more details, please write to contact at spoken hyphen tutorial dot org |
| 10.14 | Spoken Tutorial Project is a part of the Talk to a Teacher project
|
| 10.19 | It is supported by the National Mission on Education through ICT, MHRD, Government of India.
|
| 10.28 | More information on this Mission is available at spoken hyphen tutorial dot org slash NMEICT hyphen Intro |
| 10.40 | Hope you enjoyed this Perl tutorial. |
| 10.43 | This is Amol signing off.
|
| 10.46 | Thanks for joining. |
